The present invention relates generally to railroad maintenance equipment, and in particular to an apparatus that removes and inserts railroad ties. Railroad ties deteriorate over time due to weather and other factors. Thus, it becomes necessary to remove the old deteriorated railroad ties from the railroad track and replace them with new ties.
In the past, railroad ties were removed and replaced with various types of machines that were designed for that purpose. Generally, the tie replacing machines were built to roll on a railroad track and stop at a rail tie that needed replacement. Most machines have an extending member that positions a gripping device normally relative to the track and adjacent to an end of a rail tie to remove it. The gripping device has vice-like jaws that clamp onto the end of the rail tie. Then, the extending member extends normally away from the track, and thereby removes the tie from under the railroad track. The reverse operation is used to insert a new tie under the track.
Although these prior machines are able to remove and replace the railroad ties, the machines are subject to several disadvantages. One disadvantage is that the extending members on the prior machines are relatively unstable. On the prior machines, the extending members are attached to the railroad repair machine frame at the center of the members. In operation, each member has an inner portion that is slidingly engaged within an outer portion and telescopes away from the frame to position the gripping mechanism relative to the rail tie. The length of the fully extended member places stress at the attachment point where the end of the member meets the frame. This stress often causes the member to sag, work improperly or even break over time. Furthermore, some prior machines only had one extending member, which was attached to a pivot, in order to remove ties from the other side of a track if necessary. These machines experienced additional stress at the attachment point due to the excess movement and vibration on the extending member.
More recently developed machines include two extending members, one on each side of the machine, that are mounted along the same axis. A main support member is situated in the middle of the machine frame and contains the two extending members which are slidingly engaged with each other. This innermost member extends in an opposite direction from the next outer member. In operation, one extending member slides outward within the main support member, and away from the machine frame, towards the location of the rail tie.
The dual in-line extending member design increases efficiency and overcomes the stress experienced by the single pivoting extending member design. These machines can remove a rail tie from either side of a track without pivoting, however stress problems still occur when the extending member is completely extended away from the frame. The full extension places most of the weight of the extending member on the minimal contact point between the extending member and the main support member. Stress is created on the contact point between the main support member and extending member, and failure results.
Another disadvantage with these prior machines is that one long hydraulic cylinder is used to extend a member on either side of the machine. The hydraulic cylinder is attached between the ends of each extending member and fully extends during operation of either extending member. This configuration lacks stability and the full extension of the long hydraulic cylinder eventually leads to sagging and failure, which adds to repair time and costs.
A further disadvantage with prior machines is the use of relatively long wear pads to reduce sliding friction between each extending member and the main support member. The wear pads facilitate smooth movement of the extending members within the main support member, however, uneven wear and xe2x80x9cslopxe2x80x9d results from operation.
First, the wear pads extend from the outer end of one extending member to the outer end of the other extending member. The sliding friction between the members wears down the pads. Since the prior machines include at least three telescoping units to an extending member, the combined wear of the pads on each unit creates a cumulative excessive displacement or xe2x80x9cslopxe2x80x9d between the telescoping elements. The cumulative displacement of the telescoping elements of each extending member causes the extending members to sag over time, which restricts the movement of the extending member and reduces its operational efficiency.
Second, the wear on the pads tends to vary along the length of the pads. In most instances, one side of a pad will wear more quickly than the other side. Regardless of which side of the pad wears more quickly, the entire elongated pad still needs to be replaced. Also in the prior machines, the extending members have to be completely disassembled to remove the pads. This process takes substantial time and effort. In addition, while most of the pads are still in good condition, the pads must be replaced due to the wear on only one side. As a result, replacing these pads in this manner is expensive and wasteful.
Yet another disadvantage of conventional railway repair machines is that these machines utilize an extending member configured with three slidingly engaged tubes. Two smaller sized tubes slide within a larger main tube that is connected to the frame of the machine. The smaller sized tubes are each attached to a gripping device and one of these tubes slides within the other tube. Therefore, one extending member is made of a tube that is smaller than the other extending member so that it can slide within the other extending member. This three tube configuration makes replacement of the extending members more difficult and more expensive because each extending member is unique and not interchangeable.
Accordingly, it is the primary object of the present invention to provide an improved rail tie replacement apparatus that includes at least two non-axially aligned extending members attached to the frame and to each other at one end.
It is another object of the present invention to provide an improved rail tie replacement apparatus including fluid powered cylinders in an axial relationship to each other and operate in unison to facilitate faster reciprocal movement of the extending members over prior railway maintenance machines.
It is yet another object of the present invention to provide an improved rail tie replacement apparatus including fluid powered cylinders in an axial relationship to each other for providing increased stability and reducing the incidence of malfunction of the extending members.
It is a further object of the present invention to provide an improved rail tie replacement apparatus having a plurality of wear pads on the ends of each telescoping element of an extending member, to reduce the stress on the extending members and to facilitate pad replacement.
It is still a further object of the present invention to provide a rail tie replacement apparatus having extending members that are identically configured so that the members are interchangeable and may be used to replace a damaged or broken extending member on either side of the apparatus, which provides a reduced inventory and reduction of parts.
The above-listed objects are met or exceeded by the present rail tie replacement apparatus, which features non-axially aligned extending members disposed in a side-by-side relationship, with one member extending in a first direction to service one side of the track and the other extending in an opposite direction to service the other side of the track. The non-axial relationship enhances the stability of the extending members because the members are supported both by the frame and by each other. As the extending members operate on either side of the frame, the stability and operation of the machine is greatly improved over the existing machine due to the non-axial positioning of the extending members on the frame.
Another feature of the present rail tie replacement apparatus is at least two fluid powered cylinders connected to each other at one end and configured to operate in unison to facilitate the stable reciprocal movement of the extending members. Yet another feature of the present apparatus is removable wear pads attached to the extending members. The pads are disposed at the ends of the extending members for easy replacement.
More specifically, the present invention provides a rail tie replacement apparatus that includes a frame having a first side associated with a first side of a railroad track, and a second side associated with a second side of a railroad track. Gripping mechanisms disposed on each side of the frame and are configured for grasping rail ties located in the railroad track. Extending members are attached to the frame and include a first extending member and a second extending member in a non-axial relationship to each other. The extending members are configured for positioning said gripping means relative to the rail ties.